Double bimetallic gaseous relay



A. H. LAIDIG Oct. 14, 941.

DOUBLE BIMETALLIC GASEOUS RELAY Filed Aug. 14, 1940 y l gaaaunuannnvbINVENTOR M f/p/a.

mLswrrwL TTORNEY Patented Oct. 14, 1941 2,259,111 DOUBLE BIMETALLICGASEOUS RELAY Alfred B. Laidig, Bloomeld, N. J., assignor toWestinghouse Electric &

Pittsburgh,

pany, East Pennsylvania Manufacturing Com- Pa., a corporation ofApplication August 14, 1940, Serial No. 352,500

(Cl. Z50-27.5)

Claims.

My invention relates to gaseous discharge devices and especially togaseous discharge thermal relays.

An object of my invention `is to provide a gaseous discharge thermalrelay in which the ambient temperature does not affect the normalspacing between the electrodes.

Another object of the invention is to prevent distortion of theelectrodes during heat treatment and exhaust of the device.

Another object of the invention is to provide a gaseous dischargethermal relay that may be utilized near places of high temperature or inlarge size refrigerators.

Other objects and advantages of the invention will be apparent from thefollowing description and drawing in which:

Fig. 1 is a view in perspective, with parts broken away, of a preferredembodiment of the invention.

Fig. 2 is an elevational view of the device in Fig. 1 during heattreatment.

' provide bimetallic means Fig. 3 is an elevational view of the devicein I Fig. 1 during operation.

Figs. 4, 5, 6, and 7 are elevational views illustrating variousmodifications of the electrode structure of Fig. 1.

Fig. 7 is a cross-sectional view on line VII-VII of Fis. 6.

'I'he purpose of my invention is to provide a gaseous discharge thermalrelay that will not be deformed during heat treatment and exhaust commonwith such devices.

An additional object is to prevent the eil'ect of ambient temperatureson the spacing between the electrodes of such a relay. form, myinvention is an improvement on the gaseous discharge thermal relay, suchas disclosed in Patent 2,200,443 to E. C. Dench, issued May v14, 1940.Such gaseous discharge thermal relays include electrodes inside of acasing, such as the glass tube I0 disclosed in Fig. l. This tubecontains a gaseous atmosphere, such as neon. argon, or a similarionizable medium or combination of gases.

In order to make certain that the gaseous medium is pure, the variousmetal parts of the device'are heat treated, preferably by ahighfrequency induction coil II disclosed in Fig. 2. This coil is energizedduring the time that atmosphere and occluded gases in the metal partsare being exhausted through the tubulation I2. Since the device in theDench patent is to gradually close the contacts under the heat ofdischarge, such contacts will close under the eIIect In its specific ofthe heat treatment, and frequently the effect of this heat treatment isto distort the electrodes both in shape and desired spacing from oneanother.

After the device has been formed for operation in the usual roomtemperature, an installaage warehouses. The eil'ect of such aninstallation with its low ambient temperature is to considerably slow upthe action of the discharge relay. Furthermore, the device may beinstalled in a climate where the ambient temperature is always warm,with the result that the action of the relay may be accelerated toc muchby the ambient temperature.

It is specifically an object of my invention to that will automaticallycompensate for the elIect of the ambient temperature on the bimetal orbimetals affected by the discharge. This .bimetallic means is connectedto one or both of the electrodes and is designed to prevent ambienttemperature closing the contacts. With such means, the closing of thecontacts will be the sole result of a discharge between the twoelectrodes.

In Fig. l, I have disclosed a preferred embodiment in which a press I3supports two electrodes. One of these electrodes such as I4 ispreferably composed of a bimetallic strip having the metal layer oflower expansion on the side facing the other electrode I5. This otherelectrode I5 may I I. These electrodes are preferably coated with zincto provide a low work function, and at a suitable distance from theupper ends each electrode preferably has a contact area I6 to take thewear from the shock of contact. Normally these bimetallic electrodeswould be supported on standards I1 passing through the press I3.

In its preferred embodiment, I insert a bimetallic element I8 betweenthe standards I1 and a connection I9 to the bimetallic element I l. Asdisclosed in Fig. 1, I prefer to install a second bimetallic element 20between the standards I'I and the connection I9 to the bimetallicelectrode I5. The bimetallic elements I8 and 20 are arranged so that themetallic layers of lower expansion are on the outside and the metals ofhigher expansion face one another. The surface of these bimetallicelements, or at least the surfaces facing one another, may be coatedwith a material of very high work function such as aluminum oxide. Theelect of heat on the two pairs of bimetals, namely, I4 and I5, and I8and 28, is the reverse. In other words, the top ends of tht` bimetals I4and I5 will tend to contact one another, but the top portions of IB and20.

vbut at the same time the top portions of the bimetals I8 and 20 willspread further apart with the result that contact and consequentdistortion of the electrodes will not result from the high heattreatment necessary to remove the gases. After desired vacuum isobtained inside the casing I0, the induction coil II is removed and thedesired gaseous atmosphere inserted within the tube and the tubulationsealed oi.

'I'he device is now ready for installation in an arrangement such asillustrated in Fig. 1 of Dench Patent No. 2,200,443. This iig-ureillustrates one of the most common applications of my invention which isfor the purpose of starting a fluorescent lamp.

When the electrodes of my relay are connected to the lamp electrodes anda suitable source of power, a discharge will be initiated from onebimetal i4 to the other I5. This discharge will heat up the two bimetalsI4 and I5 taking part in the discharge. The bimetals IS and 20 will notbe aiected to any extent.

The result will be that the contact points I6 will close as illustratedin Fig. 3 because of the heat of discharge applied tothe two binzetals.As

y the contacts I6 close, the discharge between the two electrodes willbe short-circuited by the contact, and the discharge in-my relay willstop. 'Ihe bimetals I4 and I5 will then cool and separate. As these twobimetals separate the discharge will be initiated in the gaseousatmosphere ofthe lamp.

If desired, shields 30 may be placed around the connecting portions I9between the two b1- metals to prevent the possibility of the dischargebetween the two sets of bimetals such as from electrode I to the lowerbimetal I8.

In Fig. 5, I have illustrated an embodiment in which the electrodes haveonly one bimetal of each set. The standard 3| has an electrode extensionconsisting of a small diameter wire 32 with a contact area 33 thereon,and the other electrode comprises a standard 34 'connected to a broadstrip bimetal 35 similar to the bimetal I8 in Fig. 1 which is connectedin turn by a connection 36 to a bimetal 31 sir'nilar to the bimetal I4of Fig. 1 and having upon its upper end a con-l tact area 38. The actionof the bimetal 35 in this modiiication is to counteract the eect ofambient temperature on the bimetal 3l', as previously explained. Theconstruction of the broad on the inner side of the U. The other standard42 has an extension 43 entering the mouth of the U so that theapplication of heat to the bimetal will Amove its contact end 44 to makecontazt with the extension .43, as illustrated in dotted lines.

Intermediate the standard 42 and the contact portion 43 of thiselectrode, I preferably insert a U-shaped bimetal 45 with the metal oflower expansion on the outer side of the bimetal. The action of thebimetal 45 will be the reverse of the bimetal 44, namely, heat will movethe extension 43 away from the bimetal 44 as shown in dotted lines,whereas heat will move the bimetal 4I closer to the extension 43.

Accordingly, under the heat treatment of the induction coil illustratedin Fig. 2, the contact portion of 43 will move away from the path ofmovement of the end of the bimetal 4I and there will be no distortion.However, when the discharge. is started, the bimetal 45 will not beaffected thereby to any appreciable extent, and contact will be madebetween the two electrodes bythe movement of the bimetal 4I.

In Fig. 8, I have disclosed a still further modification oi electrodestructure in which the standard 50 has a contact-making portion .5Iadjacent the contact end 52 of an inverted and crimped bimetal 53. Thisbimetal 53 has two lateral indentations 54 near the at bottom por-- tionof the U in order that a tab of magnesium 55 may be inserted at the baseof the U and bent down at either s ide of the U to be held looselytherein. This tab oi magnesium provides the lowered work functiondesired in starting the discharge.

The inverted U-shaped bimetal has a connection 56 to a U-shaped bimetal5l having the position of its metallic layers reversed from that oi thebimetal 53. The bimetal 53 has its metal of lower expansion on the innerside and the bimetal 57 has its metal of lower expansion on the outerside. A shield 58 preferably of insulating material, intercepts anydirect discharge lines between the two bimetals so that the dischargewill beconflned to the bimetal 53 and the extension 5I of the otherelectrode. 'Ihe shield 58 in this figure as well as the shield 30 inFig. 4 acts also as a heat shield between the discharge and the lowerbimetal or bimetals.

Under the iniiuence of heat treatment as illustrated in Fig. 2, thebimetal 51 will bend the bimetal 53 to the position disclosed in dottedlines 53. In this position, contact will not be between the bimetal andthe other electrode at 5I, and

hence there will be no distortion of the electrode structure.

It is apparent that I have disclosed an arrangement whereby the eiect ofambient temperature will be automatically compensated for in the gaseousdischarge thermal relays illustrated. It

trode whereby the heat of discharge will bend said electrode intocontact with the other electrode to short-circuit said electrodes andextinguish said discharge, and a second bimetal connected to one of saidelectrodes at a place removed from the-shortest discharge path betweensaid electrodes, said second bimetal 'having its metal of lowerexpansion faced in the opposite direction to that of the lower expansionmetal of said first .bimetal whereby said second bimetal will tend tocompensate for the effect of ambient temperature on the first bimetal.

2. A gaseous discharge device comprising a container provided with anionizable medium therein, two closely spaced electrodes therein, saidelectrodes having contact areas, one of said electrodes having a bimetaladjacent said contact area with the metal of lower expansion facing thecontact area of the other electrode whereby the heat of discharge willmake said contact areas join and short-circuit said electrodes, and asecond bimetal connected to one of said electrodes at a place remotefrom said rst bimetal and having its metal of lower expansion faced inan opposite direction from that of the lower expansion metal ofsaidiirst bimetal whereby the effect of a change in ambient temperatureon one bimetal to vary the electrode spacing is compensated by theeffect on the other bimetal.

3. A gaseous discharge device comprising a container provided with anionizable medium therein, a curved bimetal having its metal of lowerexpansion on the inner side, an electrode within the curved bimetalcooperating to form a discharge path therewith, a second bimetalconnected to said bimetal ata place removed from said discharge path andadapted to move said electrode out of the'curved bimetal upon theapplication of high ambient temperature.

4: A gaseous discharge device comprising a container provided with anionizable medium therein, two electrodes forming a discharge path, oneof said electrodes having a bimetal as a terminal for the discharge pathwith its metal of lower expansion facing the other electrode whereby theheat of discharge will move the electrode into contact with the otherelectrode, said other electrode having a bimetal connected to it remotefrom the discharge path between the electrodes,

metallic element in said container adapted to be heated by. the ensuingdischarge and operable to short-circuit said electrodes and extinguishsaid discharge, bimetallic means compensating forthe effect of ambienttemperature upon said bimetallic element, and a shield interposedbetween said bimetallic element and said last mentioned b1- metallicmeans.

7. A gaseous discharge device comprising a container provided with anionizable medium therein, two closely spaced electrodes therein, one ofsaid electrodes includinga bimetal with its metal of .lower expansionfacing the other electrode whereby the heat of discharge will bend saidelectrode into contact with the other electrode to shortcircuit saidelectrodes and extinguish said discharge, and a second bimetal connectedto one of said electrodes at a place removed from the shortest dischargepath between said electrodes, said second bimetal having its metal oflower expansion faced in the opposite direction to that of the lowerexpansion metal of said rst bimetal whereby said second bimetal willtend to compensate for the effect of ambient temperature on the firstbimetal, and a shield interposed between said rst and second bimetals.

8. A gaseous discharge device comprising a containerprovided with anionizable medium therein, two closely spaced electrodes therein. saidelectrodes having contact areas, one of said electrodes having a bimetaladjacent said contact area with the metal of lower expansion facing thecontact area of the other electrode whereby the heat of discharge willmake said contact areas join and short-circuit said electrodes, and asecond bimetal connected to one of said electrodes at a place remotefrom said irst bimetal and having its metal of-lower expansion faced inan opposite direction from that of the lower expansion metal of saidfirst bimetal whereby the e'ect of a changeV in ambient temperature onone bimetal to vary said last mentioned bimetalcompensating for theeffects of variations in ambient temperature von said first mentionedbimetal.

5. A gaseous discharge device comprising a container provided with anionizable medium therein, electrodes disposed within said container andbetween which a glow discharge occurs upon the application of apotential thereto, one .of said electrodes being adapted to emitelectrons, a bimetallic element in said, container adapted to be heatedby the ensuing discharge -and operable to short-circuit said electrodesand extinguish said discharge, means compensating for the effect ofambient temperature upon said bimetallic element, and a shieldinterposed between said last mentioned means and said bimetallicelement.

` 6. A gaseous discharge device comprising a container provided with anionizable medium therein, electrodes disposed within said container andbetween which a glow discharge occurs upon the application of apotential thereto, one of said electrodes being adapted to emitelectrons. a bithe electrode spacing is compensated by the effect on theother bimetal, and a shield interposed between said first and secondbimetals.

.9. A gaseous discharge device comprising a container provided with anionizable medium therein, a. curved bimetal, having its metal of lowerexpansion on the inner side, an electrode within the curved bimetalcooperating to form a discharge path therewith, a second bimetalconnected to said bimetal at a place removed from said discharge pathand adapted tolmove said electrode out of the curvedbimetal upon theapplication of high ambient temperature, and a shield 55, interposedbetween said first and second bimetals.

10. A gaseous discharge device comprising a container provided with anionizable medium therein, two electrodes forming a` discharge path,

one of said electrodes having abimetal as a terminal for the dischargepath with its metal of lower expansion facing the other electrodewhereby the heat of discharge will move the electrode into contact withthe other electrode, said other electrode having a bimetal connectedtoit remote from the discharge path between the electrodes, said lastmentioned bimetal compensating for 'the eiiects of variations in ambienttemperature on said iirst mentioned bimetal, and a shield interposedbetween said bimetals.

NFRED H. LAIDIG.

